Safety paper and method of making same



Patented Sept. 7, 1943 Burgess W. Smith. Rochester, N. Y., asslgnor toThe Todd Company, Inc Rochester, N. Y., a

corporation of New York No Drawing.- Application March 25, 1941, SerialNo. 385,152

14 Claims. (cl. 117-1) This invention relates to class of paper known assafety paper used for checks, drafts,.bonds, or other commercialinstruments, having as its chief object the provision of advantageouspaperof this character of a comparatively simple nature,

' economical to produce, and applicable to a wide trate deeply into thebody of the paper so that it is not removable by abrasion.

Many prior types of paper have depended upon warning characters on thepaper with a substantially colorless stain producing material.

My present invention provides a further simple'and inexpensive method ofproducing such paper, having various other advantages such as sharp anddistinct warning words when developed with eradicators, the wordsforming well into the body of the paper and penetrating through totheother side to resist removal by abrasive methods, as well asaccessibility to the action of eradicating chemicals to insure rapid andthorough development of the warning color or stain, as well as beinggenerally available for making safety paper of various kinds and styles.

the bleaching out of a fugitive over-tint with eradicators to indicatethe-application of the chemical thereto. As' such protective tints maybe readily restored, the more modern types of safety paper haveadditional compounds incorporated therein to produce a stain thatinhibits successful retinting until the stain is removed. Flat stains ofthis nature are not ample protection as they could be explained'to thosewho are not aware of their significance, as a result of splashing orspilling some dark colored substance thereon. To give such developedstain significance, the active material adapted to change color witheradicators has been printed or otherwise applied so as to form latentwarning words or indicia.

It is obvious that in the use of latent warning words or indicia toindicate the application of ink eradicators, they should be provided ina way to resist removal from the paper to the greatest possible degree,and especially resistant to erasure by abrasion of the paper surface.This may be accomplished by having the stain when developed penetrate asdeeply as possible into the body of void because of its generallyrecognized signithe paper. However, it has been found diflicult to havethe latent printed warning word or symbol penetrate into the body of thepaper, as it is impractical to print the same with active ink and haveit penetrate through the paper. This is largely due to the tendency ofan ink that will penetrateto spread laterally and thereby render thewarning words orindicia indistinct and il- In accordance with thepresent invention it has been found that these advantages may beaccomplished by causing the active material to be distributed throughoutthe body of the paper. This may be done in the process of manuacture byadding it to the beater or incorporating it into the sizing, as is wellknown in the art. There are a number of active chemical materialssuitable for this purpose, such as, forexample, the sodium salts ofdiphenol, the hydrochloride of diphenylguanidine and alpha-naphthidine.These as well as a number of other chemicals suitable for the purposeare of a nature to react upon the application of eradicatorsto the paperto assume a comparatively deep or conspicuous tint or color as wellunderstoodin the art.

To the impregnated paper stock prepared in one of the above manners Ipropose to print or otherwise apply suitable warning characters orsymbols with a water-resisting or water-repelling colorless masking inkor medium in any manner that is expedient. For example, it may beprinted typographically from relief plates, or by rotogravure fromintaglio plates. Other methods of printing will be equally suitable.While various, marks, signs, and words are adapted to be readilyrecognized as expressing a warning meaning are available, it ispreferred to use the word forming the warning indicia penetrate into thepaper to any extent, it is desirable to have it do so to some degree butnot sufii'ciently for the lateral spreading to materially affect thelegibility of the warning word. Such an ink may be of a colorlesslithographic varnish but, it is desirable to substantially colorlessstain producing material being adapted to produce a conspicuous colorwhen acted upon by ink eradicators, and selectively reducing theactivity of saidjmaterial to the reaction with eradicators atpredetermined areas of the paper by printing warning words or indiciathereon with a substantially colorless masking varnish.

3. A method of making safety paper which consists in uniformlyincorporating in the paper a substantially colorless stain producingmaterial part develops the required stain. Normal application oferadicators will develop the stain on the surface leaving the wordpractically white. On continued orfrequent application of eradicatorsthere may be a development underneath the warning words or indicia butat no time will the development completely obliterate all traces of thewarning characters.

In an application filed on March 25, 1941, bearing Serial No. 385,153 Ihave described and claimed a further improved protective paper andmethod of making same. The paper described in my co-pending applicationis prepared by first modifying the surface of a finished or slack sizedpaper to vary or retard its penetrating qualities, and then applying thestain producing material adapted to penetrate into the untreatedportions of the paper. A paper and process described in this co-pendingapplication may be considered the reverse of that followed in thepresent ap-- plication.

A particular advantageous feature of my present invention resides in thefact that the background developing inhibits the removal of writing froman instrument by tracing the word with a brush or pen with aneradicator. Such methods of manipulation will not be effectual inchanging the meaning of the original writing. Obviously, the stain willbe developed in substantially the same form as the original writing asthe paper contains sufficient reactive material to reform the writingsufficiently to be legible.

It is obvious that paper manufactured in this manner may be furtherprotected against chemical or mechanical alteration by printing orotherwise applying a sensitive tint which may be solid or aconfiguration. If such an over-print is used it is not essential thatthe latent warning word be entirely invisible as such superimpositiontends to camouflage, as well known in the art.

While the foregoing discloses a satisfactory method of practicing thepresent invention to roduce a paper having its penetrating qualitiesmodified so as to admirably fulfill the purpose intended, it is not thedesire to be limited in any way of practicing the invention or to anyform of the resultant product, as both are capable of numerous changesand modifications all coming within the scope of the claims whichfollow.

I claim as my invention:

1. A method of making safety paper which consists in the initial step ofuniformly incorporating in the paper a substantially colorless stainproducing material being adapted to produce a conspicuous color whenacted upon by an ink eradicator, and then protecting the surface of theimpregnated paper at predetermined areas by the application of warningwords or indicia with a substantially colorless protective medium so asto selectively reduce the activity of said material to ink eradicatoratsaid areas.

2. A method of making safety paper which consists in uniformlyincorporating in the paper a being adapted to produce a conspicuouscolor when acted upon by the application of ink eradicators, andselectively reducing the activity of said material to the reaction withink eradicator at predetermined areas of the paper by printing warningwords or indlcia thereon with a substantially colorless water-resistantmedium.

4. The method of making safety paper which consists in uniformlyincorporating in the paper a substantially colorless material adapted tohave its color conspicuously altered by the reaction with chemicaleradicating means, and applying over the surface of the paper so treatedin a substantially colorless protective medium being capable of varyingthe response of said material to eradicating means, matter adapted toinherently convey a warning upon the application of said eradicatingmeans to the paper.

5. The method of making safety paper which consists in printing on apaper having embodied therein a substantially colorless material beingadapted to produce a conspicuous color when acted upon by chemicaleradicators, warning indicia in a substantially colorless protectivemedium to prevent said active material of the paper from being alteredat the areas printed with the warning indicia upon the application ofchemical eradicators tothe paper.

6. The method of making safety paper that is capable of developingwarning indicia upon the application of chemical eradicators, whichcomprises the step of first uniformly incorporatin in the paper asubstantially colorless material of a character adapted to produce aconspicuous color when acted upon by ink eradicators, and then printingwarning indicia on the thus treated paper with a substantially colorlessprotective varnish adapted to retard said material from being altered atthe printed areas upon the application of eradicator to the paper.

7. The method of making safety paper which consists in uniformlyincorporating in the paper a substantially colorless material beingadapted to produce a conspicuous color when acted upon by chemicaleradicators, printing over the surface of the treated paper in the formof a protective medium to vary the response of said material in thepaper at the printed areas to eradicators, and then overprinting saidpaper in relatively erasible ink, a. tint or pattern.

8. A safety paper having a substantially colorless stain producin-gmaterial uniforml incorporated therein, said material being of acharacter adapted to have its color conspicuously "altered when actedupon by ink eradicating re- 9. A safety paper havinga substantiallycolor- I less stain producing material uniformly incorporated thereinand being adapted to produce a conspicuous color when acted upon by anink printed thereon in a substantially colorless masking varnish toselectively reduce the activity of said material to ink eradicator.

10. A safety paper having uniformly incorporated therein a substantiallycolorless stain producing material being adapted to produce a cornspicuous color when acted uponby an ink eraditially colorlesswater-resisting mediumadapted to selectively reduce the activity of saidmaterial to ink eradicator.

11. A safety paper containing a colorless chemical capable of'reactingwith eradicator to produce a stain, and having applied thereon a film ofethyl cellulose in the form of warning words or indicia.

eradicating means.

at predetermined areas by the application of said '13. A safety paperhaving a substantially colorless material uniformly embodied therein ofa character to have its color conspicuously altered by'the action ofchemical eradicating means, warning indicia printed in repetitionthereon in a substantially colorless varnish to protect said cator, andmatter printed thereon in a substana material from being altered at welldefined areas upon the application of said eradicating means, and havingan overprinting in sensitive ink of a 1 tiniyor pattern adapted to beremoved by the substantially application of said chemical eradicatingmeans or by mechanical erasure. I

14. A safety paper having a substantially colorless -material embodiedtherein of a character adapted to produce a conspicuous color when actedupon by said ink eradicator, and having the su'rfaceof the paperselectively altered by warning indicia, applied thereon with aprotective medium to vary the response of said material at predeterminedareas upon the application v of said eradicating means.

. BURGESS W. SMITH.

